1. Field of the Invention
The present invention relates to a detection apparatus and a radiation detection system applicable to a medical diagnostic imaging apparatus, a non-destructive testing apparatus, an analysis apparatus using radiation, or the like.
2. Description of the Related Art
In recent years, thin-film semiconductor production technology has been used in a detection apparatus or a radiation detection apparatus realized by a combination of a switch element such as a TFT (Thin-Film Transistor) and a conversion element such as a photoelectric conversion element.
As a proposal for a structure that allows an increase in sensitivity of a detection apparatus by increasing an aperture ratio of a conversion element, U.S. Pat. No. 5,619,033 discloses a pixel with a stacked structure in which a conversion element is disposed above a switch element. U.S. Pat. No. 5,619,033 also discloses a pixel with a stacked structure in which an electrode of a conversion element electrically connected to a switch element is divided such that each pixel has its own electrode (hereinafter, such an electrode will be referred to as an individual electrode), while a semiconductor layer and an opposing electrode of the conversion element extend over a plurality of pixels without being separated.
However, in the structure disclosed in U.S. Pat. No. 5,619,033, if the space between the individual electrodes is reduced to achieve a large aperture ratio and a small pixel pitch, charges collected by adjacent pixels can interfere with each other, which can degrade a characteristic such as a spatial resolution. In view of the above, Japanese Unexamined Utility Model Registration Application Publication No. 07-032968 discloses a technique in which a dummy electrode is disposed between individual electrodes of adjacent conversion elements and the dummy electrode is maintained at a particular potential to attract a charge generated in a region between adjacent pixels.
However, if a dummy electrode is disposed between individual electrodes of adjacent conversion elements as in the technique in Japanese Unexamined Utility Model Registration Application Publication No. 07-032968, the result is an increase in the distance between adjacent individual electrodes. This can in effect cause a reduction in the aperture ratio of the detection apparatus. Furthermore, in the techniques disclosed in U.S. Pat. No. 5,619,033 and Japanese Unexamined Utility Model Registration Application Publication No. 07-032968, the increase in the distance between individual electrodes makes it difficult for the individual electrodes to absorb electric charges generated in a semiconductor layer in a region between the individual electrodes, and thus the semiconductor layer in such a region between the individual electrodes functions as a dead region in which no charge can be generated, which makes it difficult to increase the overall sensitivity of the detection apparatus.